1. Field of the Invention.
The present invention relates to apparatus for changing one or more dimensions or the edge configuration of a two dimension photographic image during photographic exposure of the image on film.
In the reproduction of images contained by photographic film, as by printing, it is frequently desirable to alter or change the dimensions or appearance of an image on photographic paper which is commonly referred to as distortion. In the layout of artwork, as for example, illustrations and/or lettering the precise size of the artwork or lettering image is ordinarily not critical, however, in reproduction of some photo images on photosensitive paper measurements become critical when the images represent printed circuits to be laminated together in forming a final multilayered board. Extending one dimension of photographic print of a printed circuit is necessary for the reason that during lamination the substrate shrinks.
The device of this invention is capable of very precise photo image size adjustments, for example, in increments of one thousandths of one percent.
2. Description of the Prior Art.
Several U.S. patents disclose photographic image distortion apparatus in which one dimension or the configuration of the image is changed with respect to the original image. Most of these prior art patents employ drive apparatus moving one photosheet mounting member relative to another at a different rate of speed and with respect to a source of light by utilizing gears and/or belt and pulley drives. The necessary tolerance between such operating components precludes precise repeatable minute setting measurements necessary in forming images for printed circuit boards.
Other known prior art apparatus is capable of providing incremental resolution equal with the capabilities of the present invention but accomplish this with precisely controlled stepper motors or variable speed drives. The stepper motor drives are relatively expensive and employ complex electronics and for this reason, it is believed, are not in general use. The variable speed drives are also relatively expensive and are not generally capable of precise repeatable results.
U.S. Pat. No. 3,126,809 discloses a photographic distortion apparatus utilizing a horizontal base provided with bar guide channels at opposite sides of the base for respectively moving a film support panel and a film mask having a lamp exposing slit with respect to a second film on the base. A motor driven shaft moves the light exposing slit and links connecting the mask and film panel to a fulcruming lever moves the film relative to the mask.
U.S. Pat. No. 3,445,165 discloses a device changing one dimension of a photographic image a predetermined dimension in one direction of the image. This device includes a stationary film exposing slit and source of light over a fixed frame which encloses a first mounting member moved rectilinear by a pinion and rack with respect to the light source and a second mounting member supporting the photographic image to be printed which is movable relative to and along the same line of rectilinear travel as the first mounting member. A linkage drive system operates to move the separate mounting structures for the image and film relative to the slit. The linkage system utilizes two angularly disposed rods carrying slide blocks. The relative movement between the separate supports are dependent on the angular positions of the rods.
The present invention is distinctive over the prior art apparatus by the simple components utilized which are easily frame mounted in a novel fashion and are relatively inexpensive and requires minimal maintenance. The device is also distinctive over the above named patents by eliminating the members moved transversely to the rectilinear movement of the photographic image and photosensitive sheet mounting members and by moving only one photo image sheet mounting member and by moving the light exposure slit transversely to or in the rectilinear direction of movement of the one image moving member.